In a liquid crystal module used for a mobile device or the like, electronic components are mounted to a flexible substrate (FPC) so as to control display of a liquid crystal display part and electrically connect a liquid crystal module to a mother board. To the FPC are mounted a driver IC for the above display control, and chip components such as capacitors, and the like. Since connection parts of the driver IC have narrow pitches, and contamination of the connection parts causes a decrease of reliability of the liquid crystal module, the driver IC is normally mounted before the chip components are mounted.
After the driver IC is mounted, as shown in FIG. 19, solder is supplied onto the FPC by a solder printer 1 and, chip components are mounted onto the FPC by a component mounting machine 2. Then, the FPC is carried into a reflow apparatus 3 having a heat source for melting the solder, whereby the solder is melted and the chip components are bonded to the FPC. In this case, if a circuit board has a thickness of approximately 1 mm and rigidity, the circuit board can be belt transferred by a conveyor. However, in a case of a flexible and film-shaped circuit board, e.g., the above FPC, as shown in FIG. 20, a method is employed in which FPCs 5 are aligned and fixed on a pallet 4, transferred and carried into the reflow apparatus 3. The reflow apparatus 3 at this time is a reflow apparatus which heats an environment in a furnace and then on the pallet 4, causes soldering operations on the FPCs 5 to be performed together.
In producing FPCs 5 of different kinds, each kind of FPC 5 on which components corresponding to each kind are mounted is transferred to the reflow apparatus. But, the reflow apparatus, which heats the environment in the furnace, has poor productivity in this case, and it is more efficient to heat only necessary portions. As such, a reflow apparatus using local heating by providing a light beam system as shown in FIG. 21 is effective. Particularly for preventing light from being applied to other than necessary portions, an arrangement is effective whereby light emitted from a light irradiation part 11 is applied only to the necessary portions through an opening 13 of a mask 12. Reference numeral 6, reference numeral 7 and reference numeral 8 in FIG. 21 indicate a chip component, IC and solder, respectively.
In producing many FPCs 5 of the same kind, productivity is improved by arranging the FPCs 5 on a pallet 4 as large as possible and executing bonding by solder on the FPCs 5 at a single time. However, there is little time in many cases, lately from determining specifications of a circuit board, to produce the circuit board because of a short life of goods, a variety of kinds, complication of design due to sophistication of functions, and fluidity of market trends, and consequently a mass production method by using a large pallet 4 cannot meet enhancing production efficiency requirements.
The production equipment indicated in FIG. 19 is based on a condition of treating large substrates, and therefore each apparatus is itself large. Particularly, the reflow apparatus which heats the environment in the furnace generally has a length of 3–5 m because of uniform heating, and the equipment is too large with respect to a circuit board having a size of approximately 2–30 mm, thereby obstructing flexible measures. The system with the solder printer 1, the component mounting machine 2 and the reflow apparatus 3 shown in FIG. 19 has a total length of as long as, e.g., 7 m.
Although the light beam system is effective in a case of components of the same kind or a small number of components, the number of chip components 6 and the number of kinds of chip components on an FPC 5 tend to increase these days in accordance with an enhanced level of function of the liquid crystal module, and therefore, setting an irradiation condition or the like becomes difficult when there are components having different light absorptances on the FPC 5. For instance, it is possible to manipulate a condition of the mask 12 for black electronic components or electronic components that are to be slightly heated, but there is a limitation imposed on meeting every component by the mask 12 alone because an adjacent solder is half melted or the like.
The present invention is devised to solve the above problems and has for its object to provide an apparatus and a method for bonding electronic components, which enable manufacturing a large number of kinds of circuit boards, each by a small amount, with a higher productivity than in the conventional art, circuit boards manufactured by the method, and an electronic component mounting apparatus having a bonder for an electronic component.